This invention relates to probes which can be inserted into liquid samples, for the purpose of using radiation transmitted through a sample to obtain spectroscopic information. The light wavelengths commonly used are in the range of 0.8 microns to 4.5 microns. The preferred method of sending light between the analytical instrumentation and the probe is fiber optic transmission.
Probes heretofore available for this purpose generally have had two major problems. One problem is excess stray light (e.g., 10% stray light) due to backscatter from air bubbles and particulate matter in the liquid sample. Another problem is sample retention due to a large gap cross-section combined with the short transmission pathlength used for many samples.